For the purpose of identifying and managing product information and preventing counterfeiting, many non-contact RFID tags including IC chips are used in commercial goods, packages, cards, documents, and the like. IC chips includes relevant information such as name and price of commercial goods. In some IC chips, information such as manufacturing date and factory or balance can be written by a reader/writer at a later date as needed. The information written in IC chips is read by a reader/writer to be used for management, sale, and use of commercial goods. In such a manner, the RFID tags have great benefits in increasing the convenience of merchandise management, increasing security, and preventing human errors (see Patent Literature 1).
RFID tags are usually attached to products or incorporated in cards. Accordingly, the RFID tags are strongly required to be compact and thin. In recent years, RFID tags have attracted attentions for use in products and the like which are conventionally managed with engraved or written lot numbers or are not managed in particular. Specifically, RFID tags have attracted attentions for use in management of high-variety small products such as glasses, watches, and medical samples. The RFID tags are helpful for management of factories, workers, manufacture dates, used materials, dimensions, properties, and stocks of commercial goods (samples). Accordingly, the RFID tags can reduce the trouble of management workers and prevent mistakes. For implementing such a convenient management system, RFID tags need to be miniaturized.
As such compact RFID tags, there is an RFID which includes an antenna (on-chip antenna) directly formed on an IC chip as illustrated in FIG. 1 but has a problem of short communication distance (not more than 1 mm). Compared with RFID tags which have communication distances of not more than 1 mm and can communicate only in substantially contact manner. RFID tags having communication distances of 2 to 3 mm or more provide better work efficiencies and higher work flexibility and are useful in sites where the RFID tags are actually used. In order to increase the communication distance of an on-chip antenna illustrated in FIG. 1, it is necessary to increase the size of the IC chip, which can increase the cost (see Patent Literatures 2 and 3).
On the other hand, as the RFID tags having comparatively long communication distances (2 to 3 mm or more), an RFID tag is used which includes an antenna formed on a film material and an IC chip mounted on the same as illustrated in FIG. 2 but has a problem of large size (a several cm square or larger) (see Patent Literature 4). The several cm square refers to a square 2 to 3 cm on a side. The same applies hereinafter.
On the other hand, some techniques to form an antenna within an IC package, which are excellent in mass production, are reported (see Patent Literatures 5 and 6).